The present invention relates to a fastening apparatus for securement of a winding assembly disposed at least partially in the air gap between a stator yoke and a rotor of an electric machine. The present invention is also directed to an electric machine incorporating such a fastening apparatus as well as to a method for making an electric machine of this type.
The winding of an electric machine, i.e. the entirety of electric conductors including their insulation, is intended to generate magnetic fields, or electric power should be produced therein through magnetic fields. Distinctions are herby made between windings in slots of the stator yoke and in the air gap of the electric machine, so-called air-gap windings.
German Pat. No. 30 03 483 A discloses a fastening arrangement for securing an air-gap winding in the stator of an electric machine, with the arrangement including wedge-shaped spacer placed circumferentially between the individual winding bars of the air-gap winding. The winding bars and the spacers are wrapped around their outer periphery by a bandage to form a unitary structure which can be pushed into the bore of the stack of laminations. The spacers are toothed in a comb-like manner, whereby the teeth project out radially beyond the winding bars so that the bandages are wound into the spaces between neighboring teeth, and the teeth are held in form-fitting manner in respective recesses of a winding carrier constructed as a non-metallic hollow cylinder.
German Pat. No. DE 21 65 678 discloses a holding apparatus for a stator winding disposed in the air gap of a synchronous generator. The holding apparatus includes two hollow cylinders which accommodate the stator winding in-between and can be pushed as a unit into the bore of the stack of laminations. The outer hollow cylinder is made of non-magnetic steel and formed with inwardly open slots for receiving the stator winding. The inner hollow cylinder is made of plastic and pushed into a bore of the outer hollow cylinder to thereby cover the slots of the outer hollow cylinder.
The conventional prior art suffers shortcomings because the holding apparatus as well as the fastening arrangement for securing the winding in the air gap require many components which must be positioned appropriately and secured, thereby rendering the installation complex and time consuming.
It would therefore be desirable and advantageous to provide an improved fastening apparatus for securing a winding assembly in an air gap of an electric machine, which obviates prior art shortcomings and which can be installed in few steps, while yet realizing a reliable operation of the electric machine.